随着科学的进步和发展，对信息的传输效率和传输质量的要求日益增高。因 此，高频段的开发成为人们关注的焦点。太赫兹波处于微波频段和红外频段之间， 具有强穿透性、高宽带和强相干性等特性。近年来，太赫兹超材料器件逐渐成为 医学成像、环境监测、天文观测和军事等领域的研究热点。通过人工设计具有亚 波长尺度的周期性材料可以实现对电磁波的操控，例如，单向无反射，非对称透射 和非对称反射等。这些现象在光二极管、滤波器和偏振转化器等应用中有着重要 的实用价值和研究意义。 我们提出两个方案研究了在太赫兹频段下的非对称透射、非对称反射和单向 无反射等。主要研究内容如下：

（1）利用不同弧长的双层铝环结构分别研究了单向无反射、非对称反射和非 对称透射现象。当 x 和 y 偏振波入射时，该结构实现了单向无反射和非对称透射 现象。同时，该结构实现了在透射和反射模式下的线到圆偏振转换。当圆偏振波 入射时，该结构不仅出现明显的单向无反射和非对称透射现象，而且改变入射角 时出现非对称透射现象。此外，在宽范围的入射角度 θ、共振器间距 t 和圆环旋转 角度 O 内，该结构实现了非对称反射和单向无反射现象。

（2）基于双层 H 型共振器研究了太赫兹波段温度可控的单向无反射、非对称 透射和非对称反射现象。研究表明：当上下两层的各向异性结构错开一定的角度 时，可分别实现线偏振波的非对称透射，非对称反射和单向无反射。同时，该方案 也可以实现圆偏振波的非对称反射和偏振转换。另外，利用温度变化调控二氧化 钒电导率，可使入射的线偏振和圆偏振波实现可控的单向无反射、非对称透射和非对称反射。

With the progress and development of science, the demand for information transmission efficiency and transmission quality is increasing day by day, so the development of high frequency band has become the focus of attention. Terahertz waves are located between the microwave frequency band and the infrared frequency band, and have the characteristics of strong penetration, high broadband and strong coherence. In recent years, terahertz metamaterial devices have gradually become a research hotspot in medical imaging, environmental monitoring, astronomical observation and military fields. By artificially designing periodic materials with sub-wavelength scales, terahertz metamaterial devices with different functions can be obtained, such as unidirectional reflectionless, asymmetric transmission and asymmetric reflection. These phenomena have important practical value and research significance in the applications of photodiodes, filters and polarization converters. We propose two schemes to study the asymmetric transmission, asymmetric reflection and unidirectional reflectionless in the terahertz frequency band. The main research contents are as follows:

（1）The phenomena of unidirectional reflectionless, asymmetric reflection and asymmetric transmission were studied by using the double-layer aluminum ring structures with different arc lengths. When x and y polarized waves are incident, the structure realizes unidirectional reflectionless and asymmetric transmission phenomenon. At the same time, the structure realizes linear to circular polarization conversion in transmission and reflection modes. When the circularly polarized wave is incident, the structure not only shows obvious unidirectional reflectionless and asymmetric transmission phenomenon, but also shows asymmetric transmission phenomenon when the incident Angle is changed. In addition, when the incidence angle θ, the distance between the two resonators t and the rotation angle of the arc O are changed, the structure can achieve stable asymmetric reflection and unidirectional reflectionless phenomenon.

（2）The phenomena of temperature controllable unidirectional reflectionless, asymmetric transmission and asymmetric reflection in terahertz band are studied based on a double-layer H-type resonator. The results show that when the anisotropic structures of the upper and lower layers are staggered at a certain Angle, the asymmetric transmission, asymmetric reflection and unidirectional reflectionless of linearly polarized waves can be realized respectively. At the same time, the scheme can also realize the asymmetric reflection and polarization conversion of circularly polarized waves. In addition, by adjusting the vanadium dioxide conductivity with the change of temperature, the incident linearly polarized and circularly polarized waves can realize the switchable unidirectional reflectionless, asymmetric transmission and asymmetric reflection.

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